Abstract
We present CO(J = 3-2) emission observations with the ASTE toward the 5′ × 5′ (or 6.6 kpc × 6.6 kpc at the distance D = 4.5 Mpc) region of the nearby barred spiral galaxy M 83. We successfully resolved the major structures, i.e., the nuclear starburst region, bar, and inner spiral arms at a resolution of 22″ (480 pc), showing a good spatial coincidence between CO and 6 cm continuum emissions. We found a global luminosity, L′CO(3-2), of 5.1 × 108 K km s-1 pc2 within the observed region. We also found L′ CO(3-2) in a disk region (0.5 < r < 3.5 kpc) of 4.2 × 108 K km s-1 pc2, indicating that (J = 3-2) emission in the disk region significantly contributes to the global L′CO(3-2). From a comparison of CO (J = 3-2) data with CO (J = 1-0) intensities measured with the Nobeyama 45-m telescope, we found that the radial profile of the CO (J = 3-2)/CO (J = 1-0) integrated intensity ratio, R3-2/1-0, is almost unity in the central region (r < 0.25 kpc), whereas it drops to a constant value, 0.6-0.7, in the disk region. The radial profile of star formation efficiencies (SFEs), determined from 6 cm radio continuum and CO (J = 1-0) emission, shows the same trend as that of R 3-2/1-0. At the bar-end (r ∼ 2.4 kpc), the amounts of molecular gas and the massive stars are enhanced when compared with other disk regions, whereas there is no excess of R3-2/1-0 and SFE in that region. This means that a simple summation of the star-forming regions at the bar-end and the disk cannot reproduce the nuclear starburst of M 83, implying that the spatial variation of the dense gas fraction traced by R3-2/1-0 governs the spatial variation of SFE in M 83.
| Original language | English |
|---|---|
| Pages (from-to) | 43-54 |
| Number of pages | 12 |
| Journal | Publications of the Astronomical Society of Japan |
| Volume | 59 |
| Issue number | 1 |
| Publication status | Published - 2007 |
| Externally published | Yes |
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Keywords
- Galaxies: individual (M 83 = NGC 5236)
- Galaxies: ISM
- Galaxies: starburst
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
Cite this
ASTE CO (3-2) observations of the barred spiral galaxy M 83 : I. Correlation between CO (3-2)/CO (1-0) ratios and star formation efficiencies. / Muraoka, Kazuyuki; Kohno, Kotaro; Tosaki, Tomoka; Kuno, Nario; Nakanishi, Kouichiro; Sorai, Kazuo; Okuda, Takeshi; Sakamoto, Seiichi; Endo, Akira; Hatsukade, Bunyo; Kamegai, Kazuhisa; Tanaka, Kunihiko; Cortes, Juan; Ezawa, Hajime; Yamaguchi, Nobuyuki; Sakai, Takeshi; Kawabe, Ryohei.
In: Publications of the Astronomical Society of Japan, Vol. 59, No. 1, 2007, p. 43-54.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - ASTE CO (3-2) observations of the barred spiral galaxy M 83
T2 - I. Correlation between CO (3-2)/CO (1-0) ratios and star formation efficiencies
AU - Muraoka, Kazuyuki
AU - Kohno, Kotaro
AU - Tosaki, Tomoka
AU - Kuno, Nario
AU - Nakanishi, Kouichiro
AU - Sorai, Kazuo
AU - Okuda, Takeshi
AU - Sakamoto, Seiichi
AU - Endo, Akira
AU - Hatsukade, Bunyo
AU - Kamegai, Kazuhisa
AU - Tanaka, Kunihiko
AU - Cortes, Juan
AU - Ezawa, Hajime
AU - Yamaguchi, Nobuyuki
AU - Sakai, Takeshi
AU - Kawabe, Ryohei
PY - 2007
Y1 - 2007
N2 - We present CO(J = 3-2) emission observations with the ASTE toward the 5′ × 5′ (or 6.6 kpc × 6.6 kpc at the distance D = 4.5 Mpc) region of the nearby barred spiral galaxy M 83. We successfully resolved the major structures, i.e., the nuclear starburst region, bar, and inner spiral arms at a resolution of 22″ (480 pc), showing a good spatial coincidence between CO and 6 cm continuum emissions. We found a global luminosity, L′CO(3-2), of 5.1 × 108 K km s-1 pc2 within the observed region. We also found L′ CO(3-2) in a disk region (0.5 < r < 3.5 kpc) of 4.2 × 108 K km s-1 pc2, indicating that (J = 3-2) emission in the disk region significantly contributes to the global L′CO(3-2). From a comparison of CO (J = 3-2) data with CO (J = 1-0) intensities measured with the Nobeyama 45-m telescope, we found that the radial profile of the CO (J = 3-2)/CO (J = 1-0) integrated intensity ratio, R3-2/1-0, is almost unity in the central region (r < 0.25 kpc), whereas it drops to a constant value, 0.6-0.7, in the disk region. The radial profile of star formation efficiencies (SFEs), determined from 6 cm radio continuum and CO (J = 1-0) emission, shows the same trend as that of R 3-2/1-0. At the bar-end (r ∼ 2.4 kpc), the amounts of molecular gas and the massive stars are enhanced when compared with other disk regions, whereas there is no excess of R3-2/1-0 and SFE in that region. This means that a simple summation of the star-forming regions at the bar-end and the disk cannot reproduce the nuclear starburst of M 83, implying that the spatial variation of the dense gas fraction traced by R3-2/1-0 governs the spatial variation of SFE in M 83.
AB - We present CO(J = 3-2) emission observations with the ASTE toward the 5′ × 5′ (or 6.6 kpc × 6.6 kpc at the distance D = 4.5 Mpc) region of the nearby barred spiral galaxy M 83. We successfully resolved the major structures, i.e., the nuclear starburst region, bar, and inner spiral arms at a resolution of 22″ (480 pc), showing a good spatial coincidence between CO and 6 cm continuum emissions. We found a global luminosity, L′CO(3-2), of 5.1 × 108 K km s-1 pc2 within the observed region. We also found L′ CO(3-2) in a disk region (0.5 < r < 3.5 kpc) of 4.2 × 108 K km s-1 pc2, indicating that (J = 3-2) emission in the disk region significantly contributes to the global L′CO(3-2). From a comparison of CO (J = 3-2) data with CO (J = 1-0) intensities measured with the Nobeyama 45-m telescope, we found that the radial profile of the CO (J = 3-2)/CO (J = 1-0) integrated intensity ratio, R3-2/1-0, is almost unity in the central region (r < 0.25 kpc), whereas it drops to a constant value, 0.6-0.7, in the disk region. The radial profile of star formation efficiencies (SFEs), determined from 6 cm radio continuum and CO (J = 1-0) emission, shows the same trend as that of R 3-2/1-0. At the bar-end (r ∼ 2.4 kpc), the amounts of molecular gas and the massive stars are enhanced when compared with other disk regions, whereas there is no excess of R3-2/1-0 and SFE in that region. This means that a simple summation of the star-forming regions at the bar-end and the disk cannot reproduce the nuclear starburst of M 83, implying that the spatial variation of the dense gas fraction traced by R3-2/1-0 governs the spatial variation of SFE in M 83.
KW - Galaxies: individual (M 83 = NGC 5236)
KW - Galaxies: ISM
KW - Galaxies: starburst
UR - http://www.scopus.com/inward/record.url?scp=34047188488&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34047188488&partnerID=8YFLogxK
M3 - Article
VL - 59
SP - 43
EP - 54
JO - Publication of the Astronomical Society of Japan
JF - Publication of the Astronomical Society of Japan
SN - 0004-6264
IS - 1
ER -